Beat egg whites lightly and add enough sugar to make icing that will hold shape. Blend in lemon juice to get desired consistency.
To finish a Christmas cake...
To ice your Christmas cake with royal icing, wait for the marzipan to dry on the cake for at least 24 hours. Then brush the marzipan with a bit of water, and spread with the royal icing. Allow the icing to harden, then decorate as desired.
How to ice a cake video
Watch our How to ice a cake video and see how to ice cakes with ease. You'll be icing perfect birthday and special occasion cakes in no time!